The present invention relates to electrical connectors for use in such automotive anti-lock braking systems, and more particularly to an electrical connector for mounting a coil onto a printed circuit board.
In an automotive anti-lock braking system (ABS), wheel-speed sensors monitor the motion of the wheels. If one of the wheels begins to lock, the peripheral wheel deceleration and wheel slip increase sharply. When these quantities exceed certain thresholds, a controller circuit, typically mounted on a printed circuit board (PCB), commands a solenoid-valve unit to stop or reduce the buildup of wheel-brake pressure until a lock up condition is no longer imminent. To alleviate pressure buildup, the solenoid rapidly actuates the brakes in a xe2x80x9cpumpingxe2x80x9d action that causes the wheel-brake pressure to undergo a succession of buildup, reduction, and holding phases.
Inductive coils in the solenoid-valve unit are typically connected to the PCB by solder joints. The coils are connected to the valve block that houses the solenoid-valve unit through a mechanical interface. Various tolerances must be accommodated in conventional mechanical interfaces, increasing their design complexity and manufacturing cost.
There is a need for a simple inductive coil structure that can be connected securely to a PCB without the need for a soldered connection while keeping the coil structure simple.
A connector according to the present invention has a coil bobbin with one or more protruding stems wrapped with a pre-tinned portion of a coil wire, such that the pre-tinned portion contacts through-holes of a printed circuit board (PCB) when the stems are inserted into the through-holes. An interference fit between the through-holes and the connector creates a tin-tin type connection system between the connector and the PCB. As a result, the design complexity of the connector is reduced, and the need to solder the connector to the PCB is eliminated.
In one embodiment, an electrical connector for establishing a solderless connection between a solenoid wire coil and a printed circuit board for use in an automotive anti-lock braking system includes a coil bobbin having at least one stem extending from a first surface thereof. A wire is wound in a coil arrangement around the coil bobbin and has a pre-tinned portion disposed over an end portion of the step for insertion into the through-hole of the PCB. A bobbin overmold covers the coil bobbin to protect the wire from harsh environmental conditions. A stem overmold can be formed over a portion of the stem, leaving the end portion of the stem exposed for connection to the PCB. A seal is optionally provided on the stem overmold at the juncture between the stem overmold and the bobbin overmold to prevent water from entering the coil area